Present research projects on space balloons favor developing scientific balloons with a generally cylindrical shape. The envelope of these balloons is generally a cylinder without a bottom illustratively implemented by the method described in the applicant's French patent No. 2,474,971, namely in the form of the assembly of N parallel gores. The balloon is made by assembling the cylinder ends after they were collapsed at the pole pieces on the envelope axis. These ends also absorb mechanically the longitudinal stresses. The devices for hooking the envelopes to the pole pieces therefore must be carefully designed to properly absorb the longitudinal tensions exerted on the envelope and to properly seal the space balloons.
The study of these hook-ups device furthermore is important because these cylindrical envelopes are the basic geometry of the high-volume balloons capable of carrying large loads. To that end, the structure retaining the gases in these balloons must withstand very large overpressures in order to permit steering them aerostatically by varying their gaseous mass. Illustratively such balloons are described in the applicant's French patent application No. 84.18798 and comprise an outer envelope assuring overpressure strength and one or more inner envelopes acting as the helium reservoir. The stresses produced by the overpressure are absorbed by the outer envelope, by grids of circumferential and longitudinal reinforcements and by an interpolar connecting means linking stresses among these different components thus allows very high overpressures of about 500 to 600 millibars.
It should be noted that the absence of substantial mechanical links other than the pole pieces, allows structural behavior very close to theory and therefore operation with realistic safety margins, provided, however, that the devices hooking the envelope to the pole pieces is very reliable. These hookup devices furthermore must assure the transmission of the longitudinal tensions acting on the inner envelopes while perfect hermetically is provided for the helium.
The primary object of the present invention is to solve the foregoing problems and to provide a device for hooking up the envelopes which is capable of meeting properly its mechanical and gas-sealing functions.
To that end, the main object of the invention is to provide a method for hooking an envelope to a fastener means allowing absorption of very high stresses while also assuring that the envelope is gas-tight.
Another object of the invention is to provide a method for hooking a tightened envelope around a fastener component by collapsing part of its sheath, thereby making it possible to homogenize the stresses in the collapsed part of this envelope.
Another object is to provide a method to hook outer longitudinal reinforcements of an envelope to a fastener component to allow absorbing large stresses.